The present invention relates to coal piping for delivering pulverized coal to coal fired steam generators and more particularly to the construction of a coal pipe orifice assembly for us in the coal supply pipes. Coal fired furnaces are typically provided with a plurality of ducts or pipes through which pulverized coal is directed to a plurality of fuel-air admission assemblies arrayed in respective vertically extending windboxes. The windboxes are disposed in one or more walls of the furnace for introducing coal and air into the furnace.
The pipes directing the coal to the respective windboxes have different lengths and different bends and thus it is necessary to balance the flow by means of orifices in each of the pipes. It has been conventional to provide such orifices intermediate end abutting axial sections of pipe. Typically the pipes are large and large couplings or bolted flanges are provided to couple the end abutting axially adjacent portions together.
The orifices require maintenance because the pulverized coal has a severe errosive effect on each orifice. This effect may result in plugging of a coal pipe or decreased performance of the furnace. Accordingly, it is necessary to frequently replace the orifices in the respective coal pipes.
The installation or inspection of a specific orifice often involves a substantial amount of time to remove the various bolts or couplings while simultaneously supporting the respective sections of pipe. More specifically, the process involves supporting the adjacent sections of pipe, removing two couplings, and removing the orifice. After that inspection or replacement, the system must be put back together by inserting the orifice, installing the couplings or bolts in the respective flanges and removing the supports for the respective pipes.